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Cisco NOL-23587-01
C H A P T E R 26
InterAS Option BThis document explains the different InterAS option B configuration options. The available options are InterAS option B, InterAS option B (with RFC 3107), and InterAS option B lite. The limitations of InterAS option B lite are taken care of by the InterAS option B feature in the NX-OS 7.2(0)D1(1) version.
The InterAS option B (with RFC 3107) implementation ensures complete IGP isolation between the data centers and WAN. When BGP advertises a particular route to ASBR, it also distributes the label which is mapped to that route.
Note While the InterAS option B lite version is available in the 6.2(2) version, the InterAS option B and InterAS option B (with RFC 3107 implementation) options are available in the 7.2(0)D1(1) version.
This chapter includes the following sections:
• Finding Feature Information, page 26-1
• Information About InterAS, page 26-2
• Licensing Requirements for InterAS Option B, page 26-4
• Guidelines and Limitations for Configuring InterAS Option B, page 26-4
• Configuring InterAS Option B, page 26-4
• Configuring InterAS Option B (with RFC 3107 implementation), page 26-8
• Configuring InterAS Option B (lite Version), page 26-13
• Verifying InterAS Option B Configuration, page 26-19
• Configuration Examples for Configuring InterAS Option B, page 26-19
• Additional References for Configuring InterAS Option B, page 26-21
• Feature History for Configuring InterAS Option B, page 26-21
Finding Feature InformationYour software release might not support all the features documented in this module. For the latest caveats and feature information, see the Bug Search Tool at https://tools.cisco.com/bugsearch/ and the release notes for your software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the “New and Changed Information” chapter or the Feature History table below.
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Chapter 26 InterAS Option BInformation About InterAS
Information About InterASAn autonomous system (AS) is a single network or group of networks that is controlled by a common system administration group and using a single, clearly defined protocol. In many cases, virtual private networks (VPNs) extend to different ASes in different geographical areas. Some VPNs must extend across multiple service providers; these VPNs are called overlapping VPNs. The connection between ASes must be seamless to the customer, regardless of the complexity or location of the VPNs.
InterAS and ASBRs
Separate ASes from different service providers can communicate by exchanging information in the form of VPN IP addresses. The ASBRs use EBGP to exchange that information. The IBGP distributes the network layer information for IP prefixes throughout each VPN and each AS. The following protocols are used for sharing routing information:
• Within an AS, routing information is shared using IBGP.
• Between ASes, routing information is shared using EBGP. EBGP allows service providers to set up an interdomain routing system that guarantees loop-free exchange of routing information between separate ASes.
The primary function of EBGP is to exchange network reachability information between ASes, including information about the list of AS routes. The ASes use EBGP border edge routers to distribute the routes, which includes label-switching information. Each border edge router rewrites the next-hop and MPLS labels.
InterAS configuration supported in this MPLS VPN can include an interprovider VPN, which is MPLS VPNs that include two or more ASes, connected by separate border edge routers. The ASes exchange routes use EBGP, and no IBGP or routing information is exchanged between the ASes.
Exchanging VPN Routing Information
ASes exchange VPN routing information (routes and labels) to establish connections. To control connections between ASes, the PE routers and EBGP border edge routers maintain a label forwarding information base (LFIB). The LFIB manages the labels and routes that the PE routers and EBGP border edge routers receive during the exchange of VPN information.
The ASes use the following guidelines to exchange VPN routing information:
• Routing information includes:
– The destination network.
– The next-hop field associated with the distributing router.
– A local MPLS label.
• A route distinguisher (RD1) is part of a destination network address. It makes the VPN IP route globally unique in the VPN service provider environment.
The ASBRs are configured to change the next-hop when sending VPN NLRIs to the IBGP neighbors. Therefore, the ASBRs must allocate a new label when they forward the NLRI to the IBGP neighbors.
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Chapter 26 InterAS Option BInformation About InterAS
Packet Forwarding
The above figure shows how packets are forwarded between ASes in an interprovider network. A single EBGP connection is established between ASBRs and the ASBRs will exchange routes associated with all local VRFs.
Packets are sent between the ASBRs through MPLS. Packets use the routing information stored in the LFIB of each ASBR.
A data packet carries two levels of labels when it traverses between the ASBR:
• The first label (IGP/Core label) directs the packet to the correct ASBR.
• The second label (VPN route label) directs the packet to the appropriate VRF.
InterAS Options
Nexus 7000/7700 series switches support the following InterAS options:
• InterAS option A- In an interAS option A network, autonomous system border router (ASBR) peers are connected by multiple subinterfaces with at least one interface VPN that spans the two ASes. These ASBRs associate each subinterface with a VPN routing and forwarding (VRF) instance and a BGP session to signal unlabeled IP prefixes. As a result, traffic between the back-to-back VRFs is IP. In this scenario, the VPNs are isolated from each other and, because the traffic is IP Quality of Service (QoS) mechanisms that operate on the IP traffic can be maintained. The downside of this configuration is that one BGP session is required for each subinterface (and at least one subinterface is required for each VPN), which causes scalability concerns as the network grows.
• InterAS option B - In an interAS option B network, ASBR ports are connected by one or more subinterfaces that are enabled to receive MPLS traffic. A Multiprotocol Border Gateway Router (MP-BGP) session distributes labeled VPN prefixes between the ASBRs. As a result, the traffic that flows between the ASBRs is labeled. The downside of this configuration is that, because the traffic is MPLS, QoS mechanisms that are applied only to IP traffic cannot be carried and the VRFs cannot be isolated. InterAS option B provides better scalability than option A because it requires only one BGP session to exchange all VPN prefixes between the ASBRs. Also, this feature provides nonstop forwarding (NSF) and Graceful Restart. The ASBRs must be directly connected in this option.
Some functions of option B are noted below:
– You can have an IBGP VPNv4/v6 session between Nexus 7000/7700 series switches within an AS and you can have an EBGP VPNv4/v6 session between data center edge routers and WAN routers.
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ASBR1 ASBR2
IGP+MPLS fortunnel label
MP-eBGP forVPNv4/VPNv6
Label Exchangebetween Gateway
ASBRs using MP-EBGP
DC1AS200
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Chapter 26 InterAS Option BLicensing Requirements for InterAS Option B
– There is no requirement for a per VRF IBGP session between data center edge routers, like in the lite version.
– LDP distributes IGP labels between ASBRs.
• InterAS option B (with BGP-3107 or RFC 3107 implementation)-
– You can have an IBGP VPNv4/v6 implementation between Nexus 7000/7700 series edge switches within an AS and you can have an EBGP VPNv4/v6 session between data center edge routers and WAN routers.
– BGP-3107 enables BGP packets to carry label information without using LDP between ASBRs.
– The label mapping information for a particular route is piggybacked in the same BGP update message that is used to distribute the route itself.
– When BGP is used to distribute a particular route, it also distributes an MPLS label which is mapped to that route. Many ISPs prefer this method of configuration since it ensures complete IGP isolation between the data centers.
• InterAS option B lite – Support for the InterAS option B feature is restricted in the Cisco NX-OS 6.2(2) release. Details are noted in the Configuring InterAS Option B (lite version) section.
Licensing Requirements for InterAS Option BThe following table shows the licensing requirements for this feature:
Guidelines and Limitations for Configuring InterAS Option BThe InterAS option B feature is not supported with BGP confederation AS.
Configuring InterAS Option B
Note The Option B implementation is applicable for the 7.2(0)D1(1) version.
Product License Requirement
Cisco NX-OS MPLS Layer 3 requires an MPLS license. For a complete explanation of the NX-OS licensing scheme, see the Cisco NX-OS Licensing Guide.
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Chapter 26 InterAS Option BConfiguring InterAS Option B
Configuring the Switch for InterAS Option B, page 26-5
Configuring BGP for InterAS Option B, page 26-6
Configuring the Switch for InterAS Option BYou enable certain features on the switch to run InterAS option B.
Prerequisites
Ensure that you are in the correct VDC (or use the switchto vdc command). The install feature-set mpls command is available only in the default VDC, and you must enable it in default VDC.
Configure VRFs on the DC edge switches with following steps:
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DC1AS100
ASBR1 ASBR2
IGP+MPLS fortunnel label
MP-eBGP forVPNv4/VPNv6
Label Exchangebetween Gateway
ASBRs using MP-EBGP
DC1AS200
Command Purpose
Step 1 configure terminal
Example:switch# configure terminal
Enters global configuration mode.
Step 2 install feature-set mpls
Example:switch(config)# install feature-set mpls
Installs the MPLS feature set in the default VDC.
Note You can only install and enable MPLS in the default VDC. Use the no form of this command to uninstall the MPLS feature set.
Step 3 feature mpls ldp
Example:switch(config)# feature mpls ldp
Enables the MPLS LDP feature on the device.
Note When the MPLS LDP feature is disabled on the device, no LDP commands are available.
Step 4 feature mpls l3vpn
Example:switch(config)# feature mpls l3vpn
Enables the MPLS Layer 3 VPN feature.
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Chapter 26 InterAS Option BConfiguring InterAS Option B
Configuring BGP for InterAS Option BTo configure BGP for InterAS option B, you need to enable this configuration on both the IBGP and EBGP sides. Refer to Figure 1 for reference.
Configure DC Edge switches with IBGP & EBGP VPNv4/v6 with the following steps:
Step 5 feature bgp
Example:switch(config)# feature bgp
Enables the BGP feature.
Step 6 vrf-context vrf-name
Example:switch(config)# vrf context VPN1
Defines the VPN routing instance by assigning a VRF name and enters VRF configuration mode.
The vrf-name argument is any case-sensitive, alphanumeric string up to 32 characters.
Step 7 rd route-target-ext-community
Example:switch(config-vrf)# rd100:1
Configures the route distinguisher. The route-distinguisher argument adds an 8-byte value to an IPv4 prefix to create a VPN IPv4 prefix.
Step 8 address-family {ipv4 | ipv6} unicast
Example:switch(config-vrf)# address-family ipv4 unicast
Specifies the IPv4 or IPv6 address family type and enters address family configuration mode.
Step 9 route-target {import | export} route-target-ext-community
Example:switch(config-vrf-af-ip4)# route-target import 1:1
Specifies a route-target extended community for a VRF as follows:
• The import keyword imports routing information from the target VPN extended community.
• The export keyword exports routing information to the target VPN extended community.
• The route-target-ext-community argument adds the route-target extended community attributes to the VRF's list of import or export route-target extended communities.
Step 10 copy running-config startup-config
Example:switch(config-vrf-af-ip4)# copy running-config startup-config
(Optional) Copies the running configuration to the startup configuration.
Command Purpose
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Chapter 26 InterAS Option BConfiguring InterAS Option B
Command Purpose
Step 1 configure terminal
Example:switch# configure terminalswitch(config)#
Enters global configuration mode.
Step 2 router bgp as-number
Example:switch(config)# router bgp 100
Enters the router BGP configuration mode and assigns an autonomous system (AS) number to the local BGP speaker device.
Step 3 neighbor ip-address
Example:switch(config-router)# neighbor 10.0.0.2
Adds an entry to the BGP or multiprotocol BGP neighbor table, and enters router BGP neighbor configuration mode.
Step 4 remote-as as-number
Example:switch(config-router-neighbor)# remote-as 200
The as-number argument specifies the autonomous system to which the neighbor belongs.
Step 5 address-family {vpnv4 | vpnv6} unicast
Example:switch(config-router-neighbor)# address-family vpnv4 unicast
Enters address family configuration mode for configuring IP VPN sessions.
Step 6 send-community {both | extended}
Example:switch(config-router-neighbor-af)# send-community both
Specifies that a communities attribute should be sent to both BGP neighbors.
Step 7 retain route-target all
Example:switch(config-router-neighbor-af)# retain route-target all
(Optional). Retains VPNv4/v6 address configuration on the ASBR without VRF configuration
Note If you have a VRF configuration on the ASBR, this command is not required.
Step 8 vrf vrf-name
Example:switch(config-router-neighbor-af)# vrf VPN1
Associates the BGP process with a VRF.
Step 9 address-family {ipv4 | ipv6} unicast
Example:switch(config-router-vrf)# address-family ipv4 unicast
Specifies the IPv4 or IPv6 address family and enters address family configuration mode.
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Chapter 26 InterAS Option BConfiguring InterAS Option B (with RFC 3107 implementation)
Configuring InterAS Option B (with RFC 3107 implementation)
Note This implementation is the same as the option B implementation (explained in the previous task), except that BGP is used to advertise labels for loopbacks of ASBRs. In the option B (without RFC 3107) implementation, a tunnel label was advertised by IGP+LDP between ASBRs. Here, BGP is used to advertise the label and there is no need to run an IGP between the ASBRs.
Configuring the Switch for InterAS Option B (with RFC 3107 implementation), page 26-8
Configuring BGP for InterAS Option B (with RFC 3107 implementation), page 26-10
Creating an ACL to filter LDP connections between the ASBRs (RFC 3107 implementation), page 26-12
Configuring the Switch for InterAS Option B (with RFC 3107 implementation)Configure VRFs on the DC edge switches with following steps.
Step 10 exit
Example:switch(config-vrf-af)# exit
Exits IPv4 address family.
Step 11 copy running-config startup-configExample:switch(config-router-vrf)# copy running-config startup-config
(Optional) Copies the running configuration to the startup configuration.
Command Purpose
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Loopback1.1.1.1
Loopback2.2.2.2
ASBR2
BGP Labeled unicast update10.1.1.2 <-- L2
BGP Labeled unicast update10.1.1.1 --> L1
10.1.1.1 10.1.1.2
MP-eBGP forVPNv4/VPNv6
DC1AS200
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Chapter 26 InterAS Option BConfiguring InterAS Option B (with RFC 3107 implementation)
Command Purpose
Step 1 configure terminal
Example:switch# configure terminal
Enters global configuration mode.
Step 2 install feature-set mpls
Example:switch(config)# install feature-set mpls
Installs the MPLS feature set in the default VDC.
Note You can only install and enable MPLS in the default VDC. Use the no form of this command to uninstall the MPLS feature set.
Step 3 feature mpls ldp
Example:switch(config)# feature mpls ldp
Enables the MPLS LDP feature on the device.
Note When the MPLS LDP feature is disabled on the device, no LDP commands are available.
Step 4 feature mpls l3vpn
Example:switch(config)# feature mpls l3vpn
Enables the MPLS Layer 3 VPN feature.
Step 5 feature bgp
Example:switch(config)# feature bgp
Enables the BGP feature.
Step 6 vrf-context vrf-name
Example:switch(config)# vrf context VPN1
Defines the VPN routing instance by assigning a VRF name and enters VRF configuration mode.
The vrf-name argument is any case-sensitive, alphanumeric string up to 32 characters.
Step 7 rd route-distinguisher
Example:switch(config-vrf)# rd 100:1
Configures the route distinguisher. The route-distinguisher argument adds an 8-byte value to an IPv4 prefix to create a VPN IPv4 prefix.
Step 8 address-family {ipv4 | ipv6} unicast
Example:switch(config-vrf)# address-family ipv4 unicast
Specifies the IPv4 or IPv6 address family type and enters address family configuration mode.
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Chapter 26 InterAS Option BConfiguring InterAS Option B (with RFC 3107 implementation)
Configuring BGP for InterAS Option B (with RFC 3107 implementation)Configure DC Edge switches with IBGP & EBGP VPNv4/v6 along with BGP labeled unicast family with following steps:
Prerequisites
Ensure that you are in the correct VDC (or use the switchto vdc command).
Step 9 route-target {import | export} route-target-ext-community
Example:switch(config-vrf-af-ip4)# route-target import 1:1
Specifies a route-target extended community for a VRF as follows:
• The import keyword imports routing information from the target VPN extended community.
• The export keyword exports routing information to the target VPN extended community.
• The route-target-ext-community argument adds the route-target extended community attributes to the VRF's list of import or export route-target extended communities.
Step 10 copy running-config startup-config
Example:switch(config-vrf-af-ip4)# copy running-config startup-config
(Optional) Copies the running configuration to the startup configuration.
Command Purpose
Command Purpose
Step 1 configure terminal
Example:switch# configure terminal
Enters global configuration mode.
Step 2 router bgp as-number
Example:switch(config)# router bgp 200
Enters the router BGP configuration mode and assigns an autonomous system (AS) number to the local BGP speaker device.
In this example, the ASBR and AS are ASBR2 and AS-200, respectively.
Step 3 address-family {ipv4 | ipv6} unicast
Example:switch(config-router)# address-family ipv4 unicast
Enters address family configuration mode for configuring IPv4 or IPv6 sessions.
Step 4 redistribute direct route-map tag
Example:switch(config-router-af)# redistribute direct route-map loopback
Redistributes directly connected routes using the Border Gateway Protocol.
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Chapter 26 InterAS Option BConfiguring InterAS Option B (with RFC 3107 implementation)
Step 5 allocate-label all Example:switch(config-router-af)# allocate-label all
Configures ASBRs with the BGP labeled unicast address family to advertise labels for the connected interface.
Step 6 exit Example:switch(config-router-af)# exit
Exits address family router configuration mode and enters router BGP configuration mode.
Step 7 neighbor ip-address
Example:switch(config-router)# neighbor 10.1.1.1
Configures the BGP neighbour’s IP address, and enters router BGP neighbour configuration mode.
Step 8 remote-as as-number
Example:switch(config-router-neighbor)# remote-as 100
Specifies the BGP neighbour’s AS number.
Step 9 address-family {ipv4|ipv6} labeled-unicast
Example:switch(config-router-neighbor)# address-family ipv4 labeled-unicast
Configures the ASBR with the BGP labeled unicast address family to advertise labels for the connected interface.
Note This is the command that implements RFC 3107.
Step 10 retain route-target all
Example:switch(config-router-neighbor-af)# retain route-target all
(Optional). Retains VPNv4/v6 address configuration on the ASBR without VRF configuration.
If you have a VRF configuration on the ASBR, this command is not required.
Step 11 exit
Example:Switch(config-router-neighbor-af)# exit
Note Enter the exit command twice.
Exits router BGP neighbour address family configuration mode and returns to router BGP configuration mode.
Step 12 neighbor ip-address
Example:switch(config-router)# neighbor 1.1.1.1
Configures a loopback IP address, and enters router BGP neighbor configuration mode.
Step 13 remote-as as-number
Example:switch(config-router-neighbor)# remote-as 100
Specifies the BGP neighbour’s AS number.
Step 14 address-family {vpnv4|vpnv6} unicast
Example:switch(config-router-neighbor)# address-family vpnv4 unicast
Configures the ASBR with the BGP VPNv4 unicast address family.
Command Purpose
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Chapter 26 InterAS Option BConfiguring InterAS Option B (with RFC 3107 implementation)
Creating an ACL to filter LDP connections between the ASBRs (RFC 3107 implementation)
Step 15 exit
Example:switch(config-router-neighbor-af)# exit
Enters router BGP neighbor configuration mode again.
Step 16 address-family {vpnv4|vpnv6} unicast
Example:switch(config-router-neighbor)# address-family vpnv6 unicast
Configures the ASBR with the BGP VPNv6 unicast address family.
Step 17 Repeat the process with ASBR2. Configures ASBR2 with option B (RFC 3107) settings and implements complete IGP isolation between the two data centers DC1 and DC2.
Step 18 copy running-config startup-config
Example:switch(config-router-neighbor-af)# copy running-config startup-config
(Optional) Copies the running configuration to the startup configuration.
Command Purpose
Command Purpose
Step 1 configure terminal
Example:switch# configure terminal
Enters global configuration mode.
Step 2 ip access-list name
Example:switch(config)# ip access-list LDP
Creates an access list and enters ACL configuration mode.
Step 3 [sequence-number] deny tcp any any eq packet-length
Example:switch(config-acl)# 10 deny tcp any any eq 646
Executes the ACL instruction as per the specified sequence.
Step 4 [sequence-number] deny tcp any eq packet-length any
Example:switch(config-acl)# 20 deny tcp any eq 646 any
Executes the ACL instruction as per the specified sequence.
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Chapter 26 InterAS Option BConfiguring InterAS Option B (lite Version)
Configuring InterAS Option B (lite Version)Guidelines and Limitations for Configuring InterAS Option B lite [applicable to the 6.2(2) release version]
• The aggregation switch supports only local VRFs, and Nexus devices within an autonomous system (AS) are connected through a VRF implementation.
• Routes learned from the IBGP peer are not sent to the EBGP peer and routes learned from an EBGP peer are not sent to IBGP VPNv4/VPNv6 peers.
Step 5 [sequence-number] deny udp any any eq packet-length
Example:switch(config-acl)# 30 deny udp any any eq 646
Executes the ACL instruction as per the specified sequence.
Step 6 [sequence-number] deny udp any eq packet-length any
Example:switch(config-acl)# 40 deny udp any eq 646 any
Executes the ACL instruction as per the specified sequence.
Step 7 [sequence-number] permit ip any any
Example:switch(config-acl)# 50 permit ip any any
Executes the ACL instruction as per the specified sequence.
Step 8 exit
Example:switch(config-acl)# exit
Exits ACL configuration mode and enters global configuration mode.
Step 9 interface type number
Example:switch(config)# interface ethernet 2/20
Enters interface configuration mode.
Step 10 mpls ip
Example:switch(config-if)# mpls ip
Configures MPLS hop-by-hop forwarding on this interface.
Step 11 ip access-group name in
Example:switch(config-if)# ip access-group LDP in
Specifies that the ACL (named LDP created in the earlier steps) be applied to inbound traffic on the interface.
Step 12 ip access-group name out
Example:switch(config-if)# ip access-group LDP out
Specifies that the ACL (named LDP created in the earlier steps) be applied to the outbound traffic on the interface.
Step 13 end
Example:switch(config-if)# end
Exits interface configuration mode and returns to the privileged EXEC mode.
Command Purpose
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Chapter 26 InterAS Option BConfiguring InterAS Option B (lite Version)
• The interAS option B with MP-BGP on the EBGP side does not work with MP-BGP on the IBGP side. One interface goes to the core and one interface goes to the Layer 3 VPN.
• MP-BGP Layer 3 VPN does not work within an AS.
This section contains information on the following topics:
• Configuring the Switch for InterAS Option B (lite version), page 26-14
• Configuring the Interfaces for InterAS Option B (lite Version), page 26-16
• Configuring BGP for InterAS Option B (lite Version), page 26-17
Configuring the Switch for InterAS Option B (lite version)You enable certain features on the switch to run interAS option B.
Prerequisites
Ensure that you are in the correct VDC (or use the switchto vdc command).
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VRF A
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P VP
N v4/
v6
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FabricPathDC
VPC DC
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iBGP VPN v4/v6
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VRF A VRF A
VRF B VRF B
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Chapter 26 InterAS Option BConfiguring InterAS Option B (lite Version)
The install feature-set mpls command is available only in the default VDC, and you must enable it in default VDC.
Command Purpose
Step 1 configure terminal
Example:switch# configure terminal
Enters global configuration mode.
Step 2 install feature-set mpls
Example:switch(config)# install feature-set mpls
Installs the MPLS feature set in the default VDC.
Note You can only install and enable MPLS in the default VDC. Use the no form of this command to uninstall the MPLS feature set.
Step 3 feature mpls ldp
Example:switch(config)# feature mpls ldp
Enables the MPLS LDP feature on the device.
Note When the MPLS LDP feature is disabled on the device, no LDP commands are available.
Step 4 feature mpls l3vpn
Example:switch(config)# feature mpls l3vpn
Enables the MPLS Layer 3 VPN feature.
Step 5 feature bgp
Example:switch(config)# feature bgp
Enables the BGP feature.
Step 6 vrf-context vrf-name
Example:switch(config)# vrf-context VPN1
Defines the VPN routing instance by assigning a VRF name and enters VRF configuration mode. The vrf-name argument is any case-sensitive, alphanumeric string up to 32 characters.
Step 7 rd route-distinguisher
Example:switch(config-vrf)# rd 100:1
Configures the route distinguisher. The route-distinguisher argument adds an 8-byte value to an IPv4 prefix to create a VPN IPv4 prefix.
Step 8 address-family {ipv4 | ipv6} unicast
Example:switch(config-vrf)# address-family ipv4 unicast
Specifies the IPv4 or IPv6 address family type and enters address family configuration mode.
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Chapter 26 InterAS Option BConfiguring InterAS Option B (lite Version)
Configuring the Interfaces for InterAS Option B (lite Version)Configure DC Edge switches with vrf-lite using the following steps.
Prerequisites
Ensure that you are in the correct VDC (or use the switchto vdc command).
Step 9 route-target {import | export} route-target-ext-community
Example:switch(config-vrf-af-ip4)# route-target import 1:1
Specifies a route-target extended community for a VRF as follows:
• The import keyword imports routing information from the target VPN extended community.
• The export keyword exports routing information to the target VPN extended community.
• The route-target-ext-community argument adds the route-target extended community attributes to the VRF's list of import or export route-target extended communities.
Step 10 copy running-config startup-config
Example:switch(config-vrf-af-ip4)# copy running-config startup-config
(Optional) Copies the running configuration to the startup configuration.
Command Purpose
Command Purpose
Step 1 configure terminal
Example:switch# configure terminal
Enters global configuration mode.
Step 2 interface type number
Example:switch(config)# interface ethernet 2/1
Specifies the interface to configure and enters interface configuration mode.
Step 3 description description
Example:switch(config-if)# description To other ASBR
Specifies a description for the interface.
Step 4 ip address prefix mask
Example:switch(config-if)# ip address 10.0.0.1 255.255.255.0
Configures IP address for interface.
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Chapter 26 InterAS Option BConfiguring InterAS Option B (lite Version)
Configuring BGP for InterAS Option B (lite Version)Prerequisites
Ensure that you are in the correct VDC (or use the switchto vdc command).
Configure EBGP VPNv4/v6 on the DC Edge switches using the following steps:
Step 5 no shutdown
Example:switch(config-if)# no shutdown
Enables interface.
Step 6 exit
Example:switch(config-if)# exit
Exits interface configuration mode and enters glbal configuration mode.
Step 7 interface type number
Example:switch(config-if)# interface ethernet 2/2
Specifies the interface to configure and enters interface configuration mode.
Step 8 description description
Example:switch(config-if)# description To CE
Specifies a description for the interface.
Step 9 vrf member vrf-name
Example:switch(config-if)# vrf member VPN1
Associates a VRF with the specified interface or subinterface. The vrf-name argument is the name assigned to a VRF.
Step 10 ip address prefix mask
Example:switch(config-if)# ip address 10.0.2.1 255.255.255.0
Configures an IP address for the interface.
Step 11 ipv6 address address
Example:switch(config-if)# ipv6 address 2001:DB8:1::1
Configures an IPv6 address for interface.
Step 12 no shutdown
Example:switch(config-if)# no shutdown
Enables the interface.
Step 13 copy running-config startup-config
Example:switch(config-if)# copy running-config startup-config
(Optional) Copies the running configuration to the startup configuration.
Command Purpose
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Chapter 26 InterAS Option BConfiguring InterAS Option B (lite Version)
DETAILED STEPS
Command Purpose
Step 1 configure terminal
Example:switch# configure terminal
Enters global configuration mode.
Step 2 router bgp as-number
Example:switch(config)# router bgp 100
Enters the router BGP configuration mode and assigns an autonomous system (AS) number to the local BGP speaker device.
Step 3 neighbor ip-address
Example:switch(config-router)# neighbor 10.0.0.2
Adds an entry to the BGP or multiprotocol BGP neighbor table.
Step 4 remote-as as-number
Example:switch(config-router-neighbor)# remote-as 200
The as-number argument specifies the autonomous system to which the neighbor belongs.
Step 5 address-family {vpnv4 | vpnv6} unicast
Example:switch(config-router-neighbor)# address-family vpnv4 unicast
Enters address family configuration mode for configuring IP VPN sessions.
Step 6 send-community {both | extended}
Example:switch(config-router-neighbor-af)# send-community both
Specifies that a communities attribute should be sent to both BGP neighbors.
Step 7 vrf vrf-name
Example:switch(config-router-neighbor-af)# vrf VPN1
Associates the BGP process with a VRF.
Step 8 address-family {ipv4 | ipv6} unicast
Example:switch(config-router-vrf)# address-family ipv4 unicast
Enters address family configuration mode for configuring IP VPN sessions.
Step 9 exit
Example:switch(config-router-vrf-af)# exit
Exits IPv4 address family.
Step 10 copy running-config startup-config
Example:switch(config-router-vrf)# copy running-config startup-config
(Optional) Copies the running configuration to the startup configuration.
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Chapter 26 InterAS Option BVerifying InterAS Option B Configuration
Verifying InterAS Option B ConfigurationTo verify InterAS option B configuration information, perform one of the following tasks:
Configuration Examples for Configuring InterAS Option B
Example: Configuring InterAS Option B !--Configure VRFs on the DC edge switches --!
configure terminalinstall feature-set mplsfeature mpls ldpfeature mpls l3vpnfeature bgpvrf context VPN1
rd 100:1 address-family ipv4 unicast
Command Purpose
show bgp {vpnv4 | vpnv6} unicast [ip-prefix/length [neighbors neighbor] ] {vrf {vrf-name | all} | rd route-distinguisher}
Displays VPN routes from the BGP table.
show bgp ipv6 unicast [vrf vrf-name] Displays information about BGP on a VRF for 6VPE.
show forwarding {ip | ipv6} route vrf vrf-name Displays the IP forwarding table that is associated with a VRF. Check that the loopback addresses of the local and remote CE routers are in the routing table of the PE routers.
show {ip | ipv6} bgp [vrf vrf-name] Displays information about BGP on a VRF.
show ip route [ip-address [mask]] [protocol] vrf vrf-name
Displays the current state of the routing table. Use the ip-address argument to verify that CE1 has a route to CE2. Verify the routes learned by CE1. Make sure that the route for CE2 is listed.
show {ip | ipv6} route vrf vrf-name Displays the IP routing table that is associated with a VRF. Check that the loopback addresses of the local and remote CE routers are in the routing table of the PE routers.
show running-config bgp Displays the running configuration for BGP.
show running-config vrf vrf-name Displays the running configuration for VRFs.
show vrf vrf-name interface if-type Verifies the route distinguisher (RD) and interface that are configured for the VRF.
trace destination [vrf vrf-name] Discovers the routes that packets take when traveling to their destination. The trace command can help isolate a problem if two routers cannot communicate.
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Chapter 26 InterAS Option BConfiguration Examples for Configuring InterAS Option B
route-target import 1:1copy running-config startup-config
!--Configure DC Edge switches with IBGP & EBGP VPNv4/v6 --!
configure terminalrouter bgp 100
neighbor 10.0.0.2 remote-as 200 address-family vpnv4 unicast
send-community both retain route-target all
vrf VPN1 address-family ipv4 unicast
exitcopy running-config startup-config
Example: Configuring InterAS Option B (RFC 3107)!--Configure VRFs on the DC edge switches --!
configure terminalinstall feature-set mplsfeature mpls ldpfeature mpls l3vpnfeature bgpvrf context VPN1
rd 100:1 address-family ipv4 unicast
route-target import 1:1copy running-config startup-config
!--Configure DC Edge switches with IBGP & EBGP VPNv4/v6 --!
configure terminalrouter bgp 100 address-family ipv4 unicast redistribute direct route-map loopback
allocate-label allexit
neighbor 10.1.1.1 remote-as 100 address-family ipv4 labeled-unicast retain route-target all exit
neighbor 1.1.1.1 remote-as 100 address-family vpnv4 unicast address-family vpnv6 unicast
!--Repeat the process with ASBR2. --! copy running-config startup-config
!--Creating an ACL to filter LDP connection between the ASBRs (RFC 3107 implementation)--!
configure terminalip access-list LDP 10 deny tcp any any eq 646 20 deny tcp any eq 646 any 30 deny udp any any eq 646 40 deny udp any eq 646 any 50 permit ip any any exit
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Chapter 26 InterAS Option BAdditional References for Configuring InterAS Option B
interface ethernet 2/20 mpls ip ip access-group LDP in ip access-group LDP out end
Additional References for Configuring InterAS Option BThis section includes the following topics:
• Related Documents, page 26-21
• MIBs, page 26-21
Related Documents
MIBs
Feature History for Configuring InterAS Option BTable 26-1 lists the release history for this feature.
Related Topic Document Title
CLI commands Cisco Nexus 7000 Series NX-OS MPLS Command Reference
Interface commands Cisco Nexus 7000 Series NX-OS Interface Command Reference
VRF-aware services Cisco Nexus 7000 Series NX-OS Unicast Routing Configuration Guide
MIBs MIBs Link
• MPLS-L3VPN-STD-MIB To locate and download MIBs, go to the following URL: http://www.cisco.com/dc-os/mibs
Table 26-1 Feature History for InterAS Option B
Feature Name Releases Feature Information
InterAS option B 7.2(0)D1(1) This feature was enhanced with the InterAS option B and InterAS option B (with RFC 3107) provisions. An IBGP VPNv4/v6 session between DC edge routers and an EBGP VPNv4/v6 session between DC edge routers and WAN routers can be established without a per VRF iBGP session between DC edge routers.
The InterAS option B (with RFC 3107) implementation ensures complete IGP isolation between the data centers and WAN.
InterAS option B lite 6.2(2) This feature was introduced as a lite version.
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Chapter 26 InterAS Option BFeature History for Configuring InterAS Option B
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